Abandoned Wells are 'Super-Emitters' of Methane

When we think of common sources of methane, usually hydraulic fracturing, or "fracking," comes to mind, and possibly microbes that dwell in rocks at the bottom of the ocean, but you probably wouldn't picture wells. Well, it turns out that abandoned wells are "super-emitters" of the greenhouse gas methane, according to a new study.

This previously unknown source of methane could be a substantial contributor to the greenhouse gas effect, leaking methane into Earth's atmosphere for decades.

"The research indicates that this is a source of methane that should not be ignored," researcher Michael Celia, a professor of civil and environmental engineering at Princeton University, said in a statement. "We need to determine how significant it is on a wider basis."

So researchers decided to sample 19 abandoned oil and natural gas wells in northern Pennsylvania, where there is a long history of oil and gas development. The wells were scattered, located everywhere from people's yards to forests, and only one of them was on the state's list of abandoned wells. (Scroll to read on...)

To conduct the research, the team placed enclosures called flux chambers over the tops of the wells, as well as nearby. This was to make sure that any leaking methane was coming from the wells themselves, and not the surrounding terrain.

They were surprised to find that every single well had at least some methane coming out of it, with certain ones leaking more than others. That is, about 15 percent of the studied wells emitted the greenhouse gas at a significantly higher level - thousands of times greater than the lower-level wells.

And with some three million abandoned wells found in the United States, this source could very well be the super emitter scientists hadn't expected.

"This may be a significant source," said researcher Denise Mauzerall. "There is no single silver bullet but if it turns out that we can cap or capture the methane coming off these really big emitters, that would make a substantial difference."

Carbon dioxide is the more infamous (and abundant) greenhouse gas polluting the atmosphere, however methane is 20 times better at trapping heat that would otherwise radiate from Earth. It is produced naturally by processes like decomposition, and through human activity like landfills and oil and gas production.

While trying to plug up every abandoned well in the country is costly, and a bit unrealistic, it might be possible to deal with the smaller number of high emitters.

The study's findings were published in the journal Proceedings of the National Academy of Sciences.

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